JPH06126615A - Polishing device for wafer - Google Patents

Abstract

PURPOSE:To keep the high degree of thickness uniformity and the flatness of a wafer so as to enable mirror-face like polishing to be carried out nicely by providing a support member for a holding plate, a ring-like elastic member, a plate-like elastic member, a closed space of a recess part and a supply means for supplying a fluid of designated pressure to the closed space. CONSTITUTION:A polishing device comprises a recess part 26 opened downward, a support member 24 for supporting a holding plate 10 not to fall down in the recess part 26, and a ring-like elastic member 34 disposed between the outer peripheral surface of the holding plate 10 and the inner peripheral surface of the recess part 26 for permitting the horizontal movement of the holding plate 10 within a very small range. The holding plate 10 is adapted to be movable within a very small range in the vertical direction and in the horizontal direction and fixed extending between the inner peripheral surface of the recess part 26 and the holding plate 10. The plate is suspended by the plate-like elastic member 38, the closed space 50 in the recess part 26 is partitioned by the plate- like elastic member 38m and a fluid with designated pressure is supplied to the closed space 50 by a supply means. Accordingly, the isobaric load can be applied to the whole surface of a wafer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polishing apparatus for wafers, and more particularly, to a polishing plate for holding a wafer on its lower surface by pressing it against a surface plate having a polishing surface on its upper surface. The present invention relates to a wafer polishing apparatus that brings the wafer surface into contact with the wafer surface and applies a predetermined load to the wafer surface, and relatively moves the wafer and the surface plate so that the wafer surface is mirror-polished.

[0002]

2. Description of the Related Art As semiconductor devices have been highly integrated in recent years, high equal thickness and flatness of silicon wafers are required. In order to meet this requirement, it is necessary to maintain the parallelism between the holding plate and the surface plate with high accuracy when polishing a silicon wafer. Conventionally, as shown in FIG. Various wafer polishing machines are used. According to this wafer polishing apparatus, the holding plate 90 is supported by the rotary shaft member 92 via the spherical bearing 91. That is, the holding plate 90 is attached to the concave spherical surface 91a of the spherical bearing 91 fixed to the rotating shaft member 92.
A convex spherical surface 90a protruding from the upper surface is slidably fitted in, and the holding plate 90 can be freely tilted following the tilt of the surface plate, thereby maintaining high parallelism and flatness. Meanwhile, the surface of the wafer 93 can be mirror-polished.

However, according to the conventional wafer polishing apparatus, the concave spherical surface 91a of the spherical bearing 91 is
Since the frictional force acts when the convex spherical surface 90a on the upper surface of the holding plate 90 slides, it is difficult for the holding plate 90 to quickly follow the inclination of the surface plate. Also, the holding plate 9
The upper surface of 0 is formed into a convex spherical surface 90a protruding in a hemispherical shape,
Since the rigidity of the member is high, the load applied to the central portion of the holding plate 90 from above can be dispersed and acted on the outer peripheral portion of the holding plate 90, but it was held by the holding plate 90. There is a problem that a constant pressure load cannot be applied to the entire surface of the wafer. For this reason, there is a problem that it is difficult to efficiently process a wafer that requires very highly accurate uniform thickness and flatness.

Therefore, an object of the present invention is to provide a load device capable of suitably following the inclination of the polishing surface of the surface plate and suitably applying a constant pressure load to the entire surface of the wafer. To provide a polishing apparatus for a wafer.

[0005]

In order to achieve the above object, the present invention has the following constitution. That is, according to the wafer polishing apparatus of the present invention, the holding plate holding the wafer on the lower surface is pressed against the surface plate having the polishing surface on the upper surface to bring the wafer surface into contact with the polishing surface. In a wafer polishing apparatus for mirror-polishing a wafer surface by relatively moving a wafer and a surface plate while applying a predetermined load to the surface, the wafer polishing apparatus has a recess opening downward, and the holding plate in the recess. A ring-shaped member that is disposed between the outer peripheral surface of the holding plate and the inner peripheral surface of the recess so as to prevent the holder plate from falling off and that allows the horizontal movement of the holding plate within a minute range. An elastic member,
Fixed between the inner surface of the recess and the holding plate,
A plate-like elastic member that suspends the holding plate in a vertical direction and a horizontal direction so as to be movable within a minute range, a closed space of the recess defined by the plate-like elastic member, and a predetermined space in the closed space. And a fluid supply means for supplying a fluid at a pressure.

[0006]

According to the wafer polishing apparatus of the present invention, the holding plate supported by the support member by the ring-shaped elastic member and the plate-shaped elastic member so as to be movable in the vertical and horizontal directions within a minute range, It is pressed against the polishing surface side of the surface plate by the pressure of the pressure fluid. Therefore, when the wafer held on the lower surface of the holding plate is brought into contact with and pressed against the polishing surface of the surface plate, the pressure fluid acts, and the wafer can quickly follow the inclination of the polishing surface. Further, since the high-pressure fluid is supplied to the space of the recess of the support member defined by the plate-shaped elastic member, it is possible to apply a constant pressure to the upper surface of the holding plate. As a result, when the wafer held on the lower surface of the holding plate is brought into contact with and pressed against the polishing surface of the surface plate, an equal pressure load can be applied to the entire surface of the wafer.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will be described in detail below with reference to the accompanying drawings. 1 is a sectional view of an essential part showing an embodiment of a wafer polishing apparatus according to the present invention, and FIG. 2 is a sectional view showing a drive mechanism and the like of the wafer polishing apparatus of the embodiment of FIG. Reference numeral 10 denotes a holding plate, which is brought into contact with the silicon wafer 1 at the lower surface 11 and can hold the silicon wafer 1 by suction. The holding plate 10 is provided with a plurality of communication holes 12 that open to the lower surface, and as shown in FIG. 1, a communication space 14 is provided horizontally at the upper end of the communication hole 12 inside the holding plate 10. Communicate with each other. The communication space 14 is connected to the suction pipe 18 via a connecting member 16. As shown in FIG. 1, the connecting member 16 is an O-ring 1.
9 is airtightly fitted to the suction pipe 18, and the connecting member 16 is airtightly fitted to the holding plate 10 via an O-ring 17. As a result, the communication space 14 and the suction pipe 18 are communicated with each other while leaving some freedom between the suction pipe 18 and the holding plate 10.

Reference numeral 20 shown in FIG. 2 is a surface plate, and a polishing cloth is usually attached to the upper surface of the surface plate, whereby a polishing surface 22 for polishing the surface of the silicon wafer 1 is formed.
A polishing liquid containing a slurry is supplied to the polishing surface 22, and the surface of the silicon wafer 1 held on the lower surface of the holding plate 10 is brought into contact with and pressed against the polishing surface 22 while a predetermined load is applied thereto. By moving the silicon wafer 1 and the surface plate 20 relative to each other, the silicon wafer 1
The surface can be mirror-polished. Further, the rotation direction of the surface plate 20 is normally rotatably provided in the same direction as the rotation of the holding plate 10 holding the silicon wafer 1 on the lower surface, and the rotation of the rotation axis causes a difference in rotation speed between the silicon plate 1 and the rotation plate. The surface of the silicon wafer 1 is mirror-polished by the relative movement of the surface of the wafer 1 and the polishing surface 22.

Reference numeral 24 is a support member, which has a concave portion 26 that opens downward, and is formed by a projection-like engaging portion 26a provided on the entire circumference of the end portion of the outer peripheral side wall portion forming the concave portion 26. The holding plate 10 can be supported so that the holding plate 10 does not fall out of the recess 26. The support member 24 includes a rod-shaped rotating shaft portion 2 along the central axis.
8 is provided upward. This rotating shaft 2
8, a through hole 30 is penetrated along the axis,
The suction pipe 18 is fitted in the through hole 30. The diameter of the through hole 30 is formed to be slightly larger than the outer shape of the suction pipe 18, and the gap between the inner wall of the through hole 30 and the outer wall of the suction pipe 18 serves as a communication passage 32 for compressed air that is a high-pressure fluid. ing.

Reference numeral 34 denotes a ring-shaped elastic member, which is made of, for example, an O-ring member made of rubber or the like.
The ring-shaped elastic member 34 is arranged so as to abut both the outer peripheral surface 10a of the holding plate and the inner peripheral surface 24a of the recess, and moves the holding plate 10 in the horizontal direction within a very small range. Tolerate. As a result, the horizontal acting force generated when the silicon wafer 1 is polished can be properly absorbed. Reference numeral 36 denotes a ring-shaped regulating member, which is fitted in the recess 26 of the support member 24. The ring-shaped regulating member 36 is made of, for example, a resin material such as Delrin so as not to damage the holding plate 10, and the holding plate 10 does not move in the recess 26 in the horizontal direction beyond a predetermined range. So that the movement of the holding plate 10 is restricted.

Reference numeral 38 denotes a plate-shaped elastic member, which is formed into a donut shape by, for example, a hard rubber plate material, is fixed between the inner surface of the recess 26 and the upper surface of the holding plate 10, and holds the holding plate 10. It is hung so that it can move vertically and horizontally within a very small range. As shown in FIG. 1, the position at which the plate-shaped elastic member 38 is fixed to the inner surface of the recess 26 is a step portion 24b provided on the entire circumference of the periphery of the recess 26.
The upper surface near the outer edge of the plate-shaped elastic member 38 is brought into contact with the surface of the stepped portion 24b, is sandwiched by the fixing plate 40, and is tightened with the screw 42 to be airtight and fixed. The lower surface of the plate-shaped elastic member 38 near the inner edge portion is in contact with the upper surface of the holding plate 10 and is airtight and fixed in the same manner as the fixing means for fixing the outer edge portion.
That is, the support member 24 is provided at the outer peripheral portion of the plate-shaped elastic member 38.
, The inner peripheral portion thereof is airtightly fixed to the holding plate 10 side, and is disposed such that the plate surface of the plate-shaped elastic member 38 is horizontal.

Reference numeral 50 denotes a closed space, which is defined by the plate-like elastic member 38 in the recess of the support member 24. A portion of the upper surface of the holding plate 10 that can come into contact with the plate-shaped elastic member 38 is provided with a diameter substantially equal to the outer diameter of the silicon wafer 1 as shown in FIG. The space 50 also extends slightly larger than the outer diameter of the silicon wafer 1. The closed space 50 communicates with the communication passage 32 for the compressed air,
When compressed air is introduced into the closed space 50 when the surface of the silicon wafer 1 is brought into contact with the polishing surface 22 of the surface plate 20, uniform pressure is applied to substantially the entire upper surface of the support member 24. . As a result, the surface of the silicon wafer 1 can be pressed against the polishing surface 22 of the surface plate 20 by applying a uniform load to the entire surface thereof with a desired pressure. At this time, since the compressed air filled in the closed space 50 is a fluid, the entire surface of the holding plate 10 can be pressed uniformly and the surface of the silicon wafer 1 can be quickly followed by the inclination of the polishing surface 22 of the surface plate 20. it can.

As shown in FIG. 2, reference numeral 52 is a base member for supplying the silicon wafer 1 held by the holding plate 10 onto the polishing surface 22 of the surface plate 20 and discharging it from the polishing surface 22. The support member 24 that supports the holding plate 10 is movably supported and rotatably supported. Reference numeral 54 denotes a locking portion, which is provided above the rotary shaft portion 28 of the support member 24 in the drawing of FIG. 2 and has upper and lower portions formed in a flange shape, and a rod 57 of the cylinder device 56.
It is locked to the arm portion 58 which is fixed to the above through a bearing in the direction of rotation and thrust. Thereby, the support member 24
Is suspended upward by the cylinder device 56. Further, the support member 24 has the rotation shaft portion 28 fitted into the rotation transmission member 60 rotatably provided with respect to the base member 52 via the thrust bearing 62, whereby the base member 52 is provided. On the other hand, it is guided so that it can move vertically. Therefore, the support member 24 can be moved up and down within a predetermined range by driving the cylinder device 56.

Reference numeral 64 denotes a drive motor, which is a pinion gear 6
6 and the driven gear 68, the driven gear 68 rotates the rotation transmission member 60 connected by the key 69. It should be noted that the rotation transmitting member 60 is provided with the rotation bearing 53 arranged between the rotation transmitting member 60 and the base member 52.
It is rotatably provided with respect to 2. Reference numeral 70 denotes a key portion, which is formed integrally with the rotation transmitting member 60 and engages with a key groove 72 provided in the rotary shaft portion 28. As a result, the support member 24 can rotate together with the rotation transmission member 60. The key groove 72 is formed vertically long along the axis, and even if the support member 24 is moved in the vertical direction by the cylinder device 56 as described above, the engagement between the key portion 70 and the key groove 72 is maintained. Can be maintained.

Reference numeral 74 is a low pressure source connection port, which is a connection port for communicating with a vacuum generation source. Reference numeral 76 is a high pressure source connection port, which is a connection port for communicating with the compressed air generation source. Reference numeral 78 denotes a seal member, and the suction pipe 18 is preferably communicated with the low pressure source connection port 74.
The case portion 79 and the rotary shaft portion 28 are preferably hermetically sealed so that the communication passage 32 for the compressed air is preferably communicated with the high pressure source connection port 76. Reference numeral 80 is an O-ring, which hermetically seals between the rotary shaft portion 28 and the suction pipe 18.

With respect to the wafer polishing apparatus having the above-described structure, its function and effect will be described with reference to FIG. First, the inside of the communication space 14 and the communication passage 12 is decompressed by the vacuum generation source communicating with the suction pipe 18, so that the silicon wafer 1 is sucked and held on the lower surface of the holding plate 10. In this state, the base member 52 is moved to convey the silicon wafer 1 to above the surface plate 20, and the cylinder device 56 further lowers the support member 24 to lower the surface of the silicon wafer 1 to the surface plate. It is brought into contact with the polishing surface 22 of 20.

Next, compressed air having a predetermined pressure is sealed in the closed space 5.
By introducing 0, the surface of the silicon wafer 1 can be pressed against the polishing surface 22 with a desired pressure. At this time, since the compressed air is a fluid, the entire surface of the holding plate 10 can be uniformly pressed, and the surface of the silicon wafer 1 can quickly follow the inclination of the polishing surface 22. Further, uniform pressure can be applied to the entire upper surface of the holding plate 10 by the compressed air. Therefore, even when the surface of the silicon wafer 1 follows the inclination of the polishing surface 22, the entire surface of the silicon wafer 1 is polished to the polishing surface 22.
Can be pressed with a uniform pressure.

Then, as described above, the polishing surface 22 of the surface plate 20 is preferably loaded with the silicon wafer 1 under load.
While supplying the slurry to the upper portion, the surface plate 20 is rotated and the supporting member 24 is rotated by the power of the drive motor 64, so that the silicon wafer 1 is mirror-polished. At this time,
According to the polishing apparatus of the present invention, when the silicon wafer 1 is polished, the compressed air filled in the closed space 50 and mainly the plate-shaped elasticity are displaced against the vertical displacement caused by the inclination of the polishing surface 22 or the like. The member 38 acts and can appropriately follow. The horizontal acting force acting on the silicon wafer 1 can be appropriately absorbed by the plate-shaped elastic member 38 and the ring-shaped elastic member 34.

Further, the support member 24 and the holding plate 10
Is connected by a plate-shaped elastic member 38 whose plate surfaces are horizontally arranged. Therefore, the distortion generated by the force in the direction orthogonal to the plane is also caused by the twisting force due to the rotation of the silicon wafer 1 on the horizontal plane. The amount of distortion can be kept very small compared to the amount. Therefore, even when a load is applied, the silicon wafer 1 can be rotated by suitably following the rotation of the support member 24 with the rotation of the holding plate 10, and at the same time, as described above, the surface plate 20 can be rotated. Can quickly follow the slope. The ring-shaped elastic member 3
4 also restricts the horizontal movement of the holding plate 10, and synergistically restricts the displacement of the holding plate 10, such as twisting, while the holding plate 10 moves the surface of the silicon wafer 1 to the surface plate 20. It is possible to quickly follow the inclination of. In the above-described embodiments, the case where the silicon wafer 1 is pressed against the polishing surface by the compressed air via the holding plate 10 has been described, but other fluid pressure, for example, hydraulic pressure can be used. Although various preferred embodiments of the present invention have been described above, the present invention is not limited to these embodiments, and many modifications can be made without departing from the spirit of the invention. That is.

[0020]

According to the wafer polishing apparatus having the above-described structure, when the wafer held on the lower surface of the holding plate is brought into contact with and pressed against the polishing surface of the surface plate, a ring-shaped elastic member, The wafer surface can quickly follow the inclination of the polishing surface by the action of the plate-shaped elastic member and the high-pressure fluid supplied to the closed space of the recess of the support member defined by the plate-shaped elastic member, and Even when the wafer surface follows the inclination of the polishing surface as described above, the entire surface of the wafer can be pressed against the polishing surface with a uniform pressure. Therefore, according to the wafer polishing apparatus of the present invention, the wafer surface can be favorably mirror-polished while maintaining a high uniform thickness and flatness of the wafer.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of a wafer polishing apparatus according to the present invention.

2 is a cross-sectional view showing a drive mechanism and the like of the wafer polishing apparatus of the embodiment of FIG.

FIG. 3 is a sectional view showing a conventional technique.

[Explanation of symbols]

 1 Silicon Wafer 10 Holding Plate 11 Holding Surface 12 Communication Passage 14 Communication Space 16 Connection Member 18 Suction Tube 20 Platen 22 Polishing Surface 24 Supporting Member 26 Recess 28 Rotating Shaft 30 Through Hole 32 Compressed Air Communication Hole 34 Ring-shaped Elasticity Member 36 Ring-shaped regulating member 38 Plate-shaped elastic member 50 Sealed space

Claims (1)

[Claims] 1. A holding plate for holding a wafer on the lower surface is pressed against a surface plate having a polishing surface on the upper surface to bring the wafer surface into contact with the polishing surface while applying a predetermined load to the wafer surface. In a wafer polishing apparatus for mirror-polishing a surface of a wafer by relatively moving the wafer and a surface plate, there is a recess opening downward, and the holding plate is supported in the recess so as not to fall off. A support member, a ring-shaped elastic member that is arranged between the outer peripheral surface of the holding plate and the inner peripheral surface of the recess, and allows the holding plate to move in the horizontal direction within a minute range; It is fixed across the holding plate,
A plate-like elastic member that suspends the holding plate so as to be movable vertically and horizontally within a very small range, a closed space of the recess defined by the plate-like elastic member, and a predetermined space in the closed space. A wafer polishing apparatus, comprising: a fluid supply unit that supplies a fluid of a pressure.